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Darren Bly
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave Mitsky]
      #5705473 - 02/28/13 02:45 PM

Quote:

Is the reason that comets discovered by automated survey systems such as Pan-STARRS, LINEAR, and NEAT are named after the surveys simply because there are, I assume, a number of individuals involved in conducting such surveys? I've been unable to find a source that discusses this matter.

Dave Mitsky




That's my understanding. Remember Comet IRAS–Araki–Alcock? IRAS stood for Infrared Astronomical Satellite so this is really nothing new.


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BrooksObs
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Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: Phillip Creed]
      #5705514 - 02/28/13 03:02 PM

Hi, Phil. I expect that you will get a fine view indeed with those 15x70 binoculars. Actually they will be the instrument of choice for me as well for doing much of my observation of PanSTARRS.

Concerning the possibility of PanSTARRS exhibiting a perihelion asymmetry (a post-T bump) in its lightcurve, while for comets nothing can be absolutely ruled out for any given one, I would speculate that the odds for C/2011 L4 deviating much from the photometric parameters reflected by the Jan and Feb observations are vanishingly small. Perihelion asymmetry is generally not an aspect commonly displayed by dynamically "new" comets. Likewise, PanSTARRS is already proving to be extraordinarily dusty for a "new" comet, so I would not anticipate any further slowing down and holding its brightness longer during the post-T interval.

What concerns me most at present is how northern observers will interpret the comet's visual impact. The geometry between PanSTARRS and Earth are such that its dust tail will be present almost exactly side on to us, resulting in a low overall surface brightness. At the same time PanSTARRS will be seen against a portion of the sky with very few really bright stars to compare it with, compounded by its being set against a bright twilight sky (at least early on). I feel that the result will be a very wide scatter in observers' opinions as to just how bright and impressive it is. Some observers will sure consider it a very nice and bright object, while other opinions will surely range on down all the way to bitter disappointment. Certainly, no one should be in anticipation of another Comet McNaught at this point. In fact, as I had warned earlier, we will see Comet PanSTARRS under the most unfavorable viewing circumstance for any really bright comet in nearly the past half century!

BrooksObs

Edited by BrooksObs (02/28/13 03:05 PM)


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Tonk
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave Mitsky]
      #5705551 - 02/28/13 03:24 PM

Quote:

I've been unable to find a source that discusses this matter.




Try the comets-ml yahoo group - its a recuring and lengthy topic with references to the official rules etc

Short answer is yes - otherwise a comet ends up with a huge series of names.


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BrooksObs
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Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave Mitsky]
      #5705567 - 02/28/13 03:29 PM

Quote:

Is the reason that comets discovered by automated survey systems such as Pan-STARRS, LINEAR, and NEAT are named after the surveys simply because there are, I assume, a number of individuals involved in conducting such surveys? I've been unable to find a source that discusses this matter.

Dave Mitsky




Dave, I covered the answer to this question in fair detail recently in the "What scope R U gonna use for Upcoming comets!!" thread. Rather than repeat it again here, might I refer readers to that post.

BrooksObs

Edited by BrooksObs (02/28/13 03:30 PM)


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RobK
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave Mitsky]
      #5706284 - 02/28/13 10:01 PM

Quote:

Is the reason that comets discovered by automated survey systems such as Pan-STARRS, LINEAR, and NEAT are named after the surveys simply because there are, I assume, a number of individuals involved in conducting such surveys? I've been unable to find a source that discusses this matter.

Dave Mitsky




This link might help (or not!):
http://www.icq.eps.harvard.edu/cometnames.html

"Today there are numerous professional CCD survey programs that scan the sky most clear nights of each month looking for near-earth objects (NEOs), which are usually minor planets (or more rarely, comets) that pass -- or can pass -- within about 0.1 AU of the earth. Convention is now that most comets found by such surveys, which each employ numerous people, are labelled/named usually (but not always) for the survey program name; thus, we have some 117 comets labelled "LINEAR" as of Sept. 2003, 35 comets labelled for "NEAT", nine comets labelled for "LONEOS", seven comets labelled "Spacewatch", four comets labelled "Catalina", and three comets labelled "Tsuchinshan", Sometimes two-member teams will get both names on a comet, but two names is a firm limit for such teams; occasionally a single astronomer from a large-survey program will be the observer, discoverer, and communicator of a new comet discovery, and such individual names are in such cases sometimes allowed to go with the comet rather than the team name."

Cheers -

Rob


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Tonk
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Re: Comet C/2011 L4 (PANSTARRS) [Re: RobK]
      #5706578 - 03/01/13 03:54 AM

Quote:

occasionally a single astronomer from a large-survey program will be the observer, discoverer, and communicator of a new comet discovery, and such individual names are in such cases sometimes allowed to go with the comet rather than the team name




E.g. McNaught or Garradd (etc) otherwise in this case they would be labelled "Siding Springs" - this does happen if Rob or Gordon submit the object as an asteroid and it later turns out from someones elses observation to be a comet (e.g. C/2013 A1)


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Dave Mitsky
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Re: Comet C/2011 L4 (PANSTARRS) [Re: BrooksObs]
      #5706582 - 03/01/13 04:01 AM

Quote:

Quote:

Is the reason that comets discovered by automated survey systems such as Pan-STARRS, LINEAR, and NEAT are named after the surveys simply because there are, I assume, a number of individuals involved in conducting such surveys? I've been unable to find a source that discusses this matter.

Dave Mitsky




Dave, I covered the answer to this question in fair detail recently in the "What scope R U gonna use for Upcoming comets!!" thread. Rather than repeat it again here, might I refer readers to that post.

BrooksObs




Thanks, John. I found a page that discussed the matter briefly after I posted my query here.

Dave Mitsky


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Dave Mitsky
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Re: Comet C/2011 L4 (PANSTARRS) [Re: RobK]
      #5706585 - 03/01/13 04:05 AM

Quote:

Quote:

Is the reason that comets discovered by automated survey systems such as Pan-STARRS, LINEAR, and NEAT are named after the surveys simply because there are, I assume, a number of individuals involved in conducting such surveys? I've been unable to find a source that discusses this matter.

Dave Mitsky




This link might help (or not!):
http://www.icq.eps.harvard.edu/cometnames.html

"Today there are numerous professional CCD survey programs that scan the sky most clear nights of each month looking for near-earth objects (NEOs), which are usually minor planets (or more rarely, comets) that pass -- or can pass -- within about 0.1 AU of the earth. Convention is now that most comets found by such surveys, which each employ numerous people, are labelled/named usually (but not always) for the survey program name; thus, we have some 117 comets labelled "LINEAR" as of Sept. 2003, 35 comets labelled for "NEAT", nine comets labelled for "LONEOS", seven comets labelled "Spacewatch", four comets labelled "Catalina", and three comets labelled "Tsuchinshan", Sometimes two-member teams will get both names on a comet, but two names is a firm limit for such teams; occasionally a single astronomer from a large-survey program will be the observer, discoverer, and communicator of a new comet discovery, and such individual names are in such cases sometimes allowed to go with the comet rather than the team name."

Cheers -

Rob




Thanks, Rob. The following link within the article that you linked spelled out the convention clearly.

http://www.ss.astro.umd.edu/IAU/csbn/cnames.shtml

Dave Mitsky


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pogrzex
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Reged: 01/25/13

Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave Mitsky]
      #5707021 - 03/01/13 11:25 AM

Looks like there is a chance to get a bit brighter than 2 mag. Still biggest question is just how will it look in my 10x50's. 3 degree tail (or more) is in my opinion minimum to be called "exctiting view" any chances for that?

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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: pogrzex]
      #5709030 - 03/02/13 03:47 PM

Latest update concerning Comet PanSTARRS' brightness. A couple of further brightness observations from recent days indicates that the comet continues to brighten nicely. A new reduction of selected available magnitude estimates is illustrated in the graph below.



The resulting magnitude formula reads as follows:

m1 = 5.6 + 5 log(D) + 7.5 log(r)

The comet's currently projected maximum brightness based on this formula is between +1.5 and +2.0 for a couple of days around March 10th, with PanSTARRS remaining a bit brighter thereafter than earlier envisioned.

BrooksObs


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Dave Mitsky
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Re: Comet C/2011 L4 (PANSTARRS) [Re: BrooksObs]
      #5709067 - 03/02/13 04:10 PM

Things are looking up, so to speak, for Comet PanSTARRS. I've seen a couple of reports of the comet having reached naked-eye visibility. There's a photo taken over light-polluted Melbourne on March 2nd posted at http://spaceweather.com/gallery/indiv_upload.php?upload_id=77081

Dave Mitsky


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Jure Atanackov
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Reged: 05/04/10

Re: Comet C/2011 L4 (PANSTARRS) [Re: Dave Mitsky]
      #5709220 - 03/02/13 05:48 PM

Also, first striae are appearing in the dust tail:

http://spaceweather.com/gallery/indiv_upload.php?upload_id=77090

CS!Jure


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OldDeadOne
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Re: Comet C/2011 L4 (PANSTARRS) [Re: Jure Atanackov]
      #5709249 - 03/02/13 06:02 PM

where in the sky will it be available for us to look for it and when? I will be using my son's binoculars

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RobK
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Reged: 07/06/08

Loc: Bright, Vic, Australia
Re: Comet C/2011 L4 (PANSTARRS) [Re: Jure Atanackov]
      #5709377 - 03/02/13 07:01 PM Attachment (20 downloads)

Hi all. The striae have been around for a few days - I imaged the comet on 01 March and if you check this image you'll see one stria extending faintly to the top of the frame, a length of about 3 degrees:
http://i727.photobucket.com/albums/ww271/Rob_Kau/C2012L401Mar2013text.jpg

We went to a mountaintop location to view the comet. That gave a flat horizon, and skies were very clear. The comet was a wonderful sight, quite bright naked-eye with a 1-degree tail showing strongly. The head looked like a moderately bright star, not as bright as nearby Fomalhaut. It became easier to see as the sky darkened but faded again as the rapidly increasing airmass near the horizon did its stuff! So there was a sweet-spot of about 15-20 mins for naked-eye viewing. The naked-eye view was not unlike this (darken the sky a little in your mind's eye!):
http://i727.photobucket.com/albums/ww271/Rob_Kau/IMG_0103sm.jpg

In binoculars it was beautiful, and clearly visible even fairly early in twilight in a light sky.

Cheers -

Rob


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RobK
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Re: Comet C/2011 L4 (PANSTARRS) [Re: RobK]
      #5709413 - 03/02/13 07:30 PM

By the way, I should add that none of the photographs around do justice to the visual view. They all burn out the head - I tried even short exposures of a second or two and none revealed the beautiful, bright little inner coma (false nucleus). What a treat you've got in store for you!!

Rob

Edited by RobK (03/02/13 07:30 PM)


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dan777
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Re: Comet C/2011 L4 (PANSTARRS) [Re: OldDeadOne]
      #5709473 - 03/02/13 07:58 PM

Quote:

where in the sky will it be available for us to look for it and when? I will be using my son's binoculars



http://www.skyandtelescope.com/skytel/beyondthepage/185665152.html


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pogrzex
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Reged: 01/25/13

Re: Comet C/2011 L4 (PANSTARRS) [Re: dan777]
      #5709895 - 03/03/13 03:11 AM

So in the first week after perihelion light pollution will not have any significant disturbing effect?

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BrooksObs
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Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: RobK]
      #5710061 - 03/03/13 07:51 AM

Quote:

Hi all. The striae have been around for a few days - I imaged the comet on 01 March and if you check this image you'll see one stria extending faintly to the top of the frame, a length of about 3 degrees:
Rob




In fact, the features that folks seem to be calling "striae" (at least based on the photos I've examined) are really the comet's different tails. The long narrow and seemingly independent appendage at the right side of the tail complex is the comet's Ion, or gas, tail. The dense central column of brighter material is the classic dust tail, which if the sky was darker would be seen to curve progressively to the left as it advances. And the left-most shorter fan with the sharp trailing edge of material represents a spray of much heavier dust, years ago referred to in comet circles as a Type III tail.

This latter feature isn't too often seen, but our current almost perfectly side-on view of PanSTARRS is providing us with the best structural view of a large comet's tail in decades. More typically our view of bright comet tails is decidedly foreshortened.

BrooksObs


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Jure Atanackov
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Reged: 05/04/10

Re: Comet C/2011 L4 (PANSTARRS) [Re: BrooksObs]
      #5710449 - 03/03/13 11:26 AM

The three different types of tails are easily discernible (we had an opportunity to see a nice Type III tail with C/2001 Q4 (NEAT) in 2004). But there are features in the 'classic' dust tail, that appear to be striae:

http://spaceweather.com/gallery/full_image.php?image_name=Minoru-Yoneto-3303_...

CS!Jure

Edited by Jure Atanackov (03/03/13 11:29 AM)


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BrooksObs
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Reged: 12/08/12

Re: Comet C/2011 L4 (PANSTARRS) [Re: Jure Atanackov]
      #5710659 - 03/03/13 01:27 PM

Quote:

The three different types of tails are easily discernible (we had an opportunity to see a nice Type III tail with C/2001 Q4 (NEAT) in 2004). But there are features in the 'classic' dust tail, that appear to be striae:

http://spaceweather.com/gallery/full_image.php?image_name=Minoru-Yoneto-3303_...

CS!Jure




Quite honestly, Jure, I see no evidence of striae in the tail in the image accompanying your post. There are some tail streamers apparent near the leading edge of the main tail, but that is it.

Tail striae originate as very brief dust outbursts/ejections from the nucleus and generally only become noticeable once they have moved fairly well out into the tail. Their long dimension will also be aligned at an angle to the axis of the main tail itself, making them look like narrow stripes across the tail (as with Comet McNaught). I really cannot say that I've seen evidence of those sorts of features in any images of PanSTARRS I've examined so far.

BrooksObs


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